Server 2008 – Ntrights Equivalent/Replacement

You should check out Windows Powershell.

http://www.microsoft.com/windowsserver2003/technologies/management/powershell/default.mspx

You could also try Cygwin if you're partial to Linux.

http://www.cygwin.com/

Make sure that you use /G and /E (edit mode) together (and most likely /T as well).

For reference, here is the complete usage information from the command CACLS /?

CACLS filename [/T] [/E] [/C] [/G user:perm] [/R user [...]]
               [/P user:perm [...]] [/D user [...]]
   filename      Displays ACLs.
   /T            Changes ACLs of specified files in
                 the current directory and all subdirectories.
   /E            Edit ACL instead of replacing it.
   /C            Continue on access denied errors.
   /G user:perm  Grant specified user access rights.
                 Perm can be: R  Read
                              W  Write
                              C  Change (write)
                              F  Full control
   /R user       Revoke specified user's access rights (only valid with /E).
   /P user:perm  Replace specified user's access rights.
                 Perm can be: N  None
                              R  Read
                              W  Write
                              C  Change (write)
                              F  Full control
   /D user       Deny specified user access.
Wildcards can be used to specify more that one file in a command.
You can specify more than one user in a command.

Abbreviations:
   CI - Container Inherit.
        The ACE will be inherited by directories.
   OI - Object Inherit.
        The ACE will be inherited by files.
   IO - Inherit Only.
        The ACE does not apply to the current file/directory.